Workpieces, including food products, are portioned or otherwise cut into smaller pieces by processors in accordance with customer needs. Also, excess fat, bone, and other foreign or undesired materials are routinely trimmed from food products. It is usually highly desirable to portion and/or trim the workpieces into uniform sizes, for example, for steaks to be served at restaurants or chicken fillets used in frozen dinners or in chicken burgers. Much of the portioning/trimming of workpieces, in particular food products, is now carried out with the use of high-speed portioning machines. These machines use various scanning techniques to ascertain the size and shape of the food product as it is being advanced on a moving conveyor. This information is analyzed with the aid of a computer to determine how to most efficiently portion the food product into optimum sizes.
Portioning machines of the foregoing type are known in the art. Such portioning machines, or portions thereof, are disclosed in prior patents, for example, U.S. Pat. Nos. 4,962,568 and 5,868,056, which are incorporated by reference herein. Typically, the workpieces are first carried by an infeed conveyor past a scanning station, whereat the workpieces are scanned to ascertain selected physical parameters, for example, their size and shape, and then to determine their weight, typically by utilizing an assumed density for the workpieces. In addition, it is possible to locate discontinuities (including voids), foreign material, and undesirable material in the workpiece, for example, bones or fat in a meat portion.
The scanning can be carried out utilizing a variety of techniques, including a video camera to view a workpiece illuminated by one or more light sources. Light from the light source is extended across the moving conveyor belt to define a sharp shadow or light stripe line. When no workpiece is being carried by the infeed conveyor, the shadow line/light stripe forms a straight line across the conveyor belt. However, when a workpiece passes across the shadow line/light stripe, the upper, irregular surface of the workpiece produces an irregular shadow line/light stripe as viewed by a video camera directed downwardly at an angle on the workpiece and the shadow line/light stripe. The video camera detects the displacement of the shadow line/light stripe from the position it would occupy if no workpiece were present on the conveyor belt. This displacement represents the thickness (or height) of the workpiece. The width of the workpiece is determined by the width of the irregular shadow line/light stripe. The length of the workpiece is determined by the length of belt travel that shadow lines/light stripes are created by the workpiece. In this regard, an encoder is integrated into the infeed conveyor, with the encoder generating pulses at fixed distance intervals corresponding to the forward movement of the conveyor.
The data and information measured/gathered by the scanning devices are transmitted to a computer, typically on board the portioning apparatus, which records the location of the workpiece on the conveyor as well as the shape and other parameters of the workpiece. With this information, the computer determines how to optimally cut or portion the workpiece at the portioning station, and the portioning may be carried out by various types of cutting/portioning devices.
Automatic portioning systems of food products, such as boneless chicken breasts, should be capable of cutting the products into uniform shape and other specifications as provided by their users. Oftentimes, the user has a reference shape that represents the user's desired shape, and a portioning system is used to portion products into the reference shape.
As the original products, such as food products, may have randomly varying geometries, it may be preferable not to apply the reference shape rigidly to every product. For example, if there are multiple products of roughly the same size but in various shapes, it may be preferable to slightly modify the reference shape with respect to each of the multiple products so as to make the maximum use of each of the products while minimizing waste. Likewise, when checking the shape of a portion that has been cut from the original product against the reference shape, it may be preferable not to apply the reference shape rigidly, since that may cause an excessive number of portions to be rejected as non-conforming to the reference shape. Therefore, a reference shape may be provided, not as a rigid shape to be found in each and every product, but as a “reference” shape from which an actual shape of a portioned piece may slightly deviate within certain geometric guidelines and boundaries. Currently, these geometric guidelines and boundaries to be used by portioning and other workpiece processing (e.g., checking) systems are arbitrarily set by the users. The users may know whether a certain shape is acceptable or not (i.e., within acceptable tolerances of the reference shape) when they see it, but may not be able to articulate the precise definition of an acceptable shape in terms of the geometric guidelines and boundaries. Therefore, it is often difficult for the users to accurately and consistently set geometric guidelines and boundaries to be used by various workpiece processing systems that define and encompass all acceptable shapes, i.e., acceptable deviations from a reference shape.
A need exists for a system and method for accurately defining an acceptable shape, or acceptable deviations from a reference shape, so as to accommodate geometric variations found in natural products, for the purpose of portioning products and/or determining whether portions that have been cut from the products have acceptable shapes.